During certain surgeries, anesthesiologists administer neuromuscular blocking agents to paralyze patients while anesthetized. This paralysis is due to neuromuscular blockade, which must be monitored during the surgery. Current techniques for monitoring the neuromuscular blockade are based on a muscle twitch response a stimulation of a peripheral nerve. For example, a peripheral nerve (e.g., the ulnar nerve, facial nerve, or posterior tibial nerve) can receive a train of four stimulation, a double burst stimulation, or a tetanus stimulation and the associated muscle twitch response can be monitored. While monitoring the twitch response due to stimulation of the ulnar nerve, the facial nerve, or the posterior tibial nerve is simple and convenient for the anesthesiologists, the muscles providing the twitch response are not a reliable measure of the strength of the neuromuscular blockade, which can lead to the patient cycling in and out of acceptable levels of neuromuscular blockade.
The diaphragm, being one of the first muscles to recover from neuromuscular blockade, is relatively resistant to neuromuscular blockade. The twitch response of the diaphragm may provide a better reflection of the degree of neuromuscular blockade that is more accurate than the traditional twitch response due to stimulation of the ulnar nerve, the facial nerve, or the posterior tibial nerve. However, the twitch response of the diaphragm is neither simple nor convenient for anesthesiologists to monitor.